The goal of exploration seismologists is to obtain the reflectivity model of the earth. This is partly achieved by collecting non-zero offset seismic data in the format of CSG's, reorganizing them into CMG's, filtering these data, applying static and NMO time shifts to correct these data to the ZO time, and stacking to get the poststack seismic section. The stacking process is the most powerful step in eliminating both coherent and random noise. For this reason and to also increase spatial resolution, offset traces with source-receiver offsets out to more than several miles are not uncommon and sections with more than 100 fold are also used. To get an even better approximation to m(x,z) the migration operator LT d is applied to these data.
Assumptions implicit in the data processing include: